Recently, image-recording materials have been developed primarily for forming color images. As such image recording materials, use may be frequently made of an ink-jet recording material, heat-sensitive transfer image recording material, xerographic recording material, transfer-system silver halide photosensitive material, printing ink, recording pen, and the like. Furthermore, color filters are used for liquid crystal displays (LCD) and plasma display panels (PDP) in displaying equipments and for electric parts such as charge-coupled devices (CCD) in photographing equipments. In these color image recording materials and color filters, full color images are reproduced or recorded by using three primary colors (dyes or pigments) of the additive color system and the subtractive color system. However, as a matter of fact, there are no dyes having an absorption property for realizing a preferable color reproduction range and usable under various use conditions. Therefore, improvement has been strongly desired.
In an ink-jet recording method, materials are not expensive, high-speed recording can be made with less noise, and color printing is easily made. For these reasons, the ink-jet recording method has rapidly come into wide use and is still undergoing development. In the ink-jet recording method, there are continuous and on-demand systems. In the continuous system, liquid droplets are continuously injected, whereas in the on-demand system, liquid droplets are injected in response to the image information signals. Liquid droplets are injected by the following systems. In a system, pressure is applied to a liquid by a piezo-electric element to inject liquid droplets. In another system, heat is applied to generate air bubbles in ink to inject liquid droplets. In still another system, an ultrasonic system is used. In still another system, an electrostatic system is used to inject liquid droplets by suctioning and injecting liquid droplets by electrostatic force. As ink suitable for ink-jet recording, mention may be made of aqueous ink, oily ink, and solid (molten state) ink, and the like.
Dye to be used in the ink suitable for ink-jet recording is required to have good solubility or dispersibility to a solvent, ability to attain high density recording, good hue, high resistance to light, heat and active gases (oxidative gas such as NOx and ozone, SOx, and others) in the environment, excellent resistance to water and chemical agents, good fixability to a recording medium with less bleeding, excellent storability as ink, no toxicity, and availability at low cost.
Furthermore, in recent years, owing to improvement of printing quality by an ink-jet printer, occasions for printing photographs have been increased. When an image of photographic quality is printed, a paper sheet called glossy paper, i.e., surface coated paper sheet, is used. However, such a surface coated paper has a problem called discoloration, which is caused by an active gas (in particular, ozone gas) in the environment. The degree of discoloration varies depending upon colors such as yellow, magenta, cyan, and black. Therefore, solving of problems raised after long time storage, that is, improving ozone resistance of each color as well as letting discoloration of colors due to ozone gas proceed at the same level have been important issues.
The dye skeleton of yellow used in aqueous ink-jet recording ink is typically an azo structure. As yellow, use may be made of C.I. Acid Yellow 17, C.I. Acid Yellow 23, C.I. Direct Yellow 86, C.I. Direct Yellow 132 and the like. Azo dyes presently on use, although some of them exhibit good hue and water resistance, are generally poor in light fastness. In particular, the level of light fastness of the yellow (azo) dye is lower than that of cyan dye represented by copper phthalocyanine dye. However, most of yellow dyes exhibit excellent ozone resistance. Because of this, discoloration of magenta, cyan, and black stands out in photographic printing. To overcome this problem, it has been desired to develop a yellow dye having an equivalent level of ozone resistance to other colors. Such a yellow dye has already been reported in the pamphlet of WO 02/081580A1 (Patent document 1). The method of synthesizing such a dye has been reported in Japanese Patent Publication (KOKOKU) No. 47-18548 (Patent document 2). However, the compound synthesized by the method reported in the publication contains a large amount of copper ions since a large amount of copper sulfate is used in a triazolization reaction. On the other hand, Japanese Patent Application Laying-Open (KOKAI) No. 2000-355665 (Patent document 4) has reported that the concentration of free copper ions contained in ink-jet recording ink is desirably reduced to 10 ppm or less. For a compound synthesized by the method described in Patent document 2 to satisfy the conditions of Patent document 4, copper ions must be removed. To do this, additional processes such as precipitation under acidic condition, salting-out, and treatment with an ion exchange resin are additionally required. This is unfavorable in manufacturing.